Merge branch 'js/merge-ort-in-read-only-repo'

In read-only repositories, "git merge-tree" tried to come up with a merge result tree object, which it failed (which is not wrong) and led to a segfault (which is bad), which has been corrected. * js/merge-ort-in-read-only-repo: merge-ort: return early when failing to write a blob merge-ort: fix segmentation fault in read-only repositories